Part 2 of Driving with Low Vision
Steven Schoenbart, OD, FIALVS, Marc J. Gannon, OD, FAAO, FIALVS, and Richard J. Shuldiner, OD, FAAO, FIALVS, Chief Clinical Editor
Last month, in Part 1, we demonstrated a case in which a woman ceased driving because her primary eye care provider gave her inaccurate information about the DMV vision rules in her state.
We also discussed the history of how acuity levels came about discovering that the vision requirements are arbitrary and not based on scientific studies. It is pretty much impossible to design a study which will tell us exactly how much visual function (acuity, field and/or contrast sensitivity) is absolutely required for safe driving. There are just too many variables; for example, time of day, weather conditions, type of roadway, etc., that require varying levels of visual function.
Lastly, we demonstrated that every state has its own rules and regulations regarding vision and driving. We strongly suggested that every eye care practitioner take the time to learn them for the benefit of their patients.
We also reiterate that vision rules change without warning. Therefore, any information found on the IALVS website or any other site may contain inaccuracies. Monitor your DMV for rules changes regularly.
As promised in Part 1, we present here the vision requirements of California and New York as examples of the differences in driving rules and regulations. We also present information on Bioptic Driving.
Visual Acuity: “The department shall not issue a driver’s license to, or renew a driver’s license of, any person whose best corrected visual acuity is 20/200 or worse in that person’s better eye, as verified by an optometrist or ophthalmologist. No person may use a bioptic telescope or similar lens to meet the 20/200 visual acuity standards.
”California has no rules regarding the use of bioptic telescopic lenses or training in the use of bioptics for driving. There is, however, an extensive table listing various eye, vision and medical conditions advising DMV agents on what to look for and do with people having these conditions.
The New York DMV’s vision standard is 20/40 in at least one eye, not less than 20/70 with a horizontal visual field of at least 140 degrees. If you are using telescopic lenses for correcting your vision, you must have used them for at least 60 days before getting your eyes tested again for licensing purposes.In NYS the following requirements must be met for renewal of the driver’s license: Once a driver attains their first NYS DMV license, the renewal for a NYS driver’s license is 8 years. To receive this license the driver must achieve the following:
- 20/40 acuity best corrected in at least one eye and a field of view of at least 140 degrees.
- If this is not attainable then the driver is referred to an eye care professional to evaluate and Dx the reduction in acuity.
Low Vision and Limited DMV License: In NYS there are 2 different tiers to be able to continue to drive legally.
- With a minimum best corrected acuity in either one or both eyes between 20/50-20/70 a driver may have a limited daytime license. The limitation as far as length of time is either 6- or 12-month renewal. This is determined by the prescribing doctor. The driver must continue to have a full 140-degree field of view. The use of expanded sideview as well as rearview mirrors is strongly recommended to help increase peripheral driving cues.
- If a driver has best corrected attainable visual acuity between 20/80 and 20/100 then we can begin evaluating their acuity with spectacle mounted bioptic telescopic glasses. The driver must achieve the following with bioptic telescopic glasses.
- 140-degree field of view looking through the carrier lenses.
- A minimum acuity of 20/40 in the better seeing eye through a telescope.
- The driver must have the bioptic glasses in their possession for a minimum of 60 days prior to letting DMV know they will be coming into DMV for a driving assessment.
- The prescribing eye care provider needs to evaluate the driver’s ability of spotting as well as scanning objects at a distance beyond the exam room. (Designs for Vision has a very nice expanded “letter/number” chart for the patient to practice at home.)
- Form 80L needs to be filled out and signed to document the driver no longer achieved the standard minimum requirements. The driver has acknowledged the ability to achieve the required acuity for driving with a limited license, either daytime only restriction or while driving wearing bioptic glasses.
- Must pass road test if he/she has not taken a road test while wearing his/her telescopic lenses.
- Eligible for a Class D or DJ driver license only.
- Ineligible for a commercial driver license (CDL), a motorcycle license or a moped license.
BIOPTIC TELESCOPIC GLASSES: CONTROVERSY, CONFUSION and FALSE ASSUMPTIONS
Bioptic telescopic glasses contain miniature telescopes, of known power, drilled and cemented into a prescription “carrier” lens. The purpose of the bioptic telescope is spotting; i.e. signs and traffic lights, similar to a rearview mirror used for spotting objects behind the car. The patient does NOT drive looking through the telescope continually due to the reduced field of view.
The reduced field of view created by telescope is often the cause of confusion, controversy and false assumptions in the eye care profession. Many eye care professionals do not understand how the system works. The patient only looks through the telescope for an instant, to view a road sign, traffic light or other object. It is exactly the same as looking through the rearview or sideview mirrors when lane changing.
The patient must be trained to shift between the carrier and the telescope for safe driving. The shifting is a very simple lowering of the head to look through the bioptics located on the top. Bioptic lenses as well as other telescopic glasses magnify images beyond the damaged area of the retina while enhancing the remaining healthy part of the retina. The patient is trained to view in the area of best retinal locus for optimal acuity through the telescope.
Once visual acuity is determined and quantified, the specific magnification of the bioptic telescopes are determined. Telescopes have various levels of magnification and fields of view available. The prescriber must determine the best retinal locus (BRL) of the patient before fitting the bioptics to make it easier for the patient to view through the telescope.
The carrier lens has the patient’s best attainable Rx to achieve a minimum acuity of whatever that state DMV requires. In New York, that is 20/100. In California, the acuity must be better than 20/200 in the better seeing eye. Each state has its own rules! The carrier lens can be single vision, bifocal or a progressive lens. It can be clear, tinted or photochromatic. Anti-reflection coating is recommended to help with glare.
While twenty feet is considered optical infinity for the eye, it is not so for telescopes. Therefore, the prescriber must calculate the refractive prescription in the telescope for true infinity. This may be different than the carrier lens Rx. Once the specific magnification of the telescopes is determined, measurements of monocular PD’s, as well as the height and angle of inclination of telescopes is determined and calculated prior to ordering bioptic telescope glasses.
There are two crucial issues for the eye care professional. The first is knowing the rules and regulations that govern vision and driving in the state the patient wants the license. The second is having several eye charts available for accurate acuity measurements.
For example, some states, like California, require one eye to have better than 20/200 acuity to pass the vision requirements. Therefore, a patient can pass with 20/190 acuity. The wrong eye chart can mean the difference between depression and independence for the patient. For example, a Snellen eye chart with a 200-size letter followed by a 100-size letter will result in the patient being told they cannot pass the vision requirements in California. That incorrect advice can be devastating to the patient.
- The patient must understand that driving is a privilege and not a right to be on the road.
- Passing the vision requirements does not give the person a license to drive. They still must demonstrate to DMV that they can safely drive.
- Bioptic telescopic glasses can help make a safe driver even safer. They cannot make an unsafe driver safe.
- Eye care professional should not, in the opinion of these authors, prejudge whether the person should or should not drive. That is the responsibility of The Department of Motor Vehicles.
Living with low vision and losing the privilege of driving, one may become depressed, anxious, angry and withdrawn from society. We must do what we can to keep the patient independent. Driving is an important factor for independence.
A referral for low vision rehabilitation is now the standard of care in the eye care profession. Consider referring you patient to the internet and have them search: “Low Vision Doctor” to find help with their vision loss situation. It might be the best advice of that patient’s life.